{ "id": "2004.04488", "version": "v1", "published": "2020-04-09T11:17:00.000Z", "updated": "2020-04-09T11:17:00.000Z", "title": "On the spectral radius of bi-block graphs with given independence number $α$", "authors": [ "Joyentanuj Das", "Sumit Mohanty" ], "categories": [ "math.CO" ], "abstract": "A connected graph is called a bi-block graph if each of its blocks is a complete bipartite graph. Let $\\mathcal{B}(\\mathbf{k}, \\alpha)$ be the class of bi-block graph on $\\mathbf{k}$ vertices with given independence number $\\alpha$. It is easy to see every bi-block graph is a bipartite graph and for a bipartite graph $G$ on $\\mathbf{k}$ vertices, the independence number $\\alpha(G)$, satisfies $\\ceil*{\\frac{\\mathbf{k}}{2}} \\leq \\alpha(G) \\leq \\mathbf{k}-1$. In this article, we prove that the maximum spectral radius $\\rho(G)$, among all graphs $G \\in \\mathcal{B}(\\mathbf{k}, \\alpha)$ is uniquely attained for the complete bipartite graph $K_{\\alpha, \\mathbf{k}-\\alpha}$.", "revisions": [ { "version": "v1", "updated": "2020-04-09T11:17:00.000Z" } ], "analyses": { "subjects": [ "05C50", "15A18" ], "keywords": [ "bi-block graph", "independence number", "complete bipartite graph", "maximum spectral radius", "connected graph" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }